1. Field of the Invention
This invention relates to mounting arrangements for printed circuit cards or boards in electrical systems and more particularly to a connector which is arranged to support and retain in electrical connection a printed wiring board.
2. Description of the Related Art
Printed circuit cards or boards have been used for many years in electronic equipment. These boards allow the many electrical devices and components to be readily connected by metallic circuits formed on one or more surfaces of the board. Today, much electronic equipment includes plug-in module boards representing entire sub-systems of electronic apparatus. The use of such an arrangement is of great assistance in facilitating assembly and diagnostic evaluation of circuit problems. Such circuit boards are usually provided with a plurality of electrical contact pads or connections along one edge of the card. The entire board is then press-fitted into a specially designed edge connector, having a plurality of mating contacts. Electrical connection beteen the card edge connector and other devices in the electrical apparatus is generally made through means of separate wiring.
Although printed wiring cards are press-fitted into card edge connectors generally, these connections do not grip the edge of the inserted board with any appreciable strength. Since the printed circuit card may need to be mounted horizontally, vertically or in some other configuration, it is naturally subject to vibration in many environments. Thus, it has generally been determined that some form of support retention means must be provided in order to securably hold the printed circuit board in position in its associated card edge connector.
Prior art apparatus generally have associated with each card edge connector for supporting such printed wiring cards one or more u-shaped channels for guiding and supporting the printed circuit card. In this arrangement, the cards are placed into these channel members which act to maintain the printed circuit boards in a spaced apart, parallel or similar relationship. It has also been determined that it is not necessary to merely guide the support for the circuit cards but that each card must be securely fastened or held within this channel in order to ensure that a proper electrical connection is made and maintained between the printed circuit board card connector pads and the associated card edge connector.
The usual solution to this problem is to include some sort of releasable locking means associated with the printed circuit card so as to securely maintain the card within the guide or support. This arrangement then allows the mounted card to be readily removed when desired. Such locking means have taken many forms such as those disclosed in U.S. Pat. Nos. 3,853,379, 3,767,974 and 3,764,857. These patents all disclose a camming or lever locking means provided in the outward end of each channel guide which engages the outer corners of the associated printed circuit card. Other techniques were disclosed in such patents as U.S. Pat. Nos. 3,798,507, 3,784,954, 3,863,113, 3,741,513 and 3,715,630.
All of the above rely in some way to engage the support and the card by means of a form of locking device or by a similar technique. Most of the above techniques require a special or modified type of printed circuit card to be used with the locking and guiding means or a special latching device or devices and associated u-shaped channel guides for each printed circuit card to be mounted.